Heat storage unit for melting of paraffin considering hybrid nanomaterial and helical tubes

In current article, spiral pipe has been employed in heat storage unit. The spiral pipe which contain the hot hybrid nanomaterial insert in the square cylinder which is full of RT82. To augment the conductivity of current paraffin, Cu with volume fraction of 0.04 has been added. The buoyancy effect has been involved in momentum equations and final PDEs were solved. Contours of streamline, temperature and liquid fraction in three time steps for two level of Re have been reported in outcomes as well as variation of Nusselt number. In both initial and end time of melting, augment of Re has no sensible impact on rate of charging but in other range of time, heat storage capacity declines with rise of time. At t = 10 min, Lf for Re=100 is 0.81% greater than that of Re=500. At Lf=0.5 and 0.8, Nusselt number augments about 46% and 34.2% with augment of Re.